There is increased recognition of the capacity for intraspecific dietary variation; however, previous studies of this phenomenon in Cercopithecus have focused only on guenons from a handful of sites. The lack of comparative and longitudinal data for West African guenons, including the Diana monkey Cercopithecus diana, inhibits our ability to assess habitat requirements, identify keystone resources, and make informed conservation decisions. Here, I present 5 years of feeding data on four Diana monkey groups ranging within the Ivory Coast’s Tai Forest. Food scans taken every 30 minutes were used to generate feeding profiles, which are interpreted through five years of phonological data collected on feeding trees.
I find significant inter-annual and monthly dietary variation in the Diana monkey diet. Though not statistically tested, monthly consumption of a particular fruit seems to be related to its abundance as shown through its phonological profile. Diana monkeys depend primarily on two fruit species, Sacoglottis gabonensis and Dialium aubrevillei, which are available during opposite seasons. Sacoglottis gabonensis is consumed during the period of lowest fruit abundance, Dialium aubrevillei during the period of highest fruit abundance. Though this would suggest that the concept of fallback foods may be relevant, I find no evidence to suggest that fallback foods provide a useful mechanism for explaining the Diana monkey diet.
Though there is significant temporal variation in the Diana monkey diet, Diana monkey group diets are remarkably similar. At Tai, Diana monkey diets comprise about 70% fruit, 25% insects, 4.6% leaves, and 0.4% other material. This is the most frugivorous of Diana monkey populations studied. Additionally, Diana monkeys are among the most frugivorous of guenon species whose diet is well studied.